Randomised control trial

Knoop K, Trott A, Syverud S.
Comparison of digital versus metacarpal blocks for repair of finger injuries.
Ann Emerg Med
1994;23:1296-1300.

Submitted by:Simon Carley - Consultant in Emergency Medicine
Institution:Manchester Royal Infirmary
Date submitted:29th November 2003

Before CA, i rated this paper: 5/10

1 Objectives and hypotheses

1.1 Are the objectives of the study clearly stated?

Yes at the end of the introduction. It was to compare efficacy and pain between the 2 types of block

2 Design

2.1 Is the study design suitable for the objectives

Yes an RCT is the best way to test this question. The use of within patient controls has advantages and disadvantages.

2.2 Who / what was studied?

30 patients convenience sample. Patients got a digital block on one side and a metacarpal block on the other. 1% lignocaine was used.

2.3 Was this the right sample to answer the objectives?

Use of within patient controls has the advantage that the patient is the same for each intervention. However, it is possible that prior injection with the MC block may affect pain on the other side when the digital block is used.

2.4 Is the study large enough to achieve its objectives? Have sample size estimates been performed?

There are no sample size calculations.

2.5 Were all subjects accounted for?

Yes. None were lost to follow up.

2.6 Were all appropriate outcomes considered?

Pain - Yes - less with digital block
Success - Yes - better with digital block
Time to anaesthesia - Yes - less with digital block

2.7 Has ethical approval been obtained if appropriate?

Not mentioned

2.8 Were the patients randomised between treatments?

This was within patient controls. Patients were randomised to either the digital ot the MC block order.

2.9 How was randomisation carried out?

Not described

2.10 Are the outcomes clinically relevant?

Yes

3 Measurement and observation

3.1 Is it clear what was measured, how it was measured and what the outcomes were?

Yes the main outcome measures were
Pain using a visual analogue scale
Success using anaesthesia to pinprick
Time

3.2 Are the measurements valid?

Yes

3.3 Are the measurements reliable?

Yes as within patient controls

3.4 Are the measurements reproducible?

Yes

3.5 Were the patients and the investigators blinded?

No. Not really possible to do. (it would make for an interesting technique!!!!)

4 Presentation of results

4.1 Are the basic data adequately described?

Yes.

4.2 Were groups comparable at baseline?

Very!

4.3 Are the results presented clearly, objectively and in sufficient detail to enable readers to make their own judgement?

Not bad. The scatter plot is particularly helpful and shows that the results are not skewed by outliers

4.4 Are the results internally consistent, i.e. do the numbers add up properly?

Yes

4.5 Were side effects reported?

There were none

5 Analysis

5.1 Are the data suitable for analysis?

Yes

5.2 Are the methods appropriate to the data?

Possible not. The authors have used parametric tests on what appears to be non parametric data.

5.3 Are any statistics correctly performed and interpreted?

5.2 suggests not

6 Discussion

6.1 Are the results discussed in relation to existing knowledge on the subject and study objectives?

Yes. There is particular reference to this being a dorsal block. A volar block could have been used and the results ofn this study should not be extrapolated to the volar technique.

6.2 Is the discussion biased?

7 Interpretation

7.1 Are the authors' conclusions justified by the data?

Yes

7.2 What level of evidence has this paper presented? (using CEBM levels)

Level 2-3 small RCT well conducted

7.3 Does this paper help me answer my problem?

Yes

After CA, i rated this paper: 7/10

8 Implementation

8.1 Can any necessary change be implemented in practice?

Currently we rarely use MC blocks. We will continue to advocate digital blocks

8.2 What aids to implementation exist?

Not applicable

8.3 What barriers to implementation exist?

Not applicable